Flotation of magnesite



Patented Nov. 21 1944 UNITED FLO'IATION OI MAGNESITE Arthur J. Welnig, Golden, 0010., assignor to Basic Magnesium, Incorporated, Las Vegas, Nev., a

corporation No Drawing. Application September 14, 1942, Serial No. 458,323

19 Claims.

positions (MgCOa) which containserpentine, hy-

dromagnesite, dolomite, forsterite or the likeas contaminating constituents. These ores are found throughout the United States and Canada and the deposit at Luning, Nevada, may be cited as typical.

For the purpose of this description, these ores have been classified according to lime content, insoluble content and magnesium oxide content, and the standard for the final product is a composition having not to exceed 2% insoluble matter and not to exceed 2% 09.0.

In general, the treatment involved in the present process is a duplication of the treatment steps disclosed in my aforementioned applications, except for reagent selection and control.

Due to a threatened shortage in coconut fatty acids because of war conditions, it has been necessary to find substitute materials in operations employing such compositions as reagents. The present invention represents discoveries made in the course of such an investigation.

It is an object of the present invention to provide a froth flotation treatment of magnesite ores producing a higher recovery and better grade product than has been attained by methods heretofore used.

Another object of the invention is to provide a froth flotation treatment of magnesite ores involving a simple combination of reagent compositions which possess a high degree of selectivity when used in small quantity.

A further object of the invention is to provide a froth flotation treatment of magnesite ores in which reagent costs are reduced without any impairment of metallurgical emciency.

Still another object of the invention is to provide a froth flotation separation of magnesite ore constituents in which a fragile froth is produced.

Other objects reside in novel steps and treatments, all of which will appear fully in the course of the following description.

In performing the process of the present invention, a pulp is produced by introducing magnesite ore in finely divided condition in a liquid carrier vehicle. A 100 mesh product may be taken as a ably includes wet grinding in closed circuit with a classifier.

The pulp is conditioned for treatment in the flotation circuit by mixing with the reagent and, if desired, this mixing may be performed in the grinding circuit by introducing the reagents at such stage, although for most operations it will be more satisfactory to employ separate conditioning tanks between the grinding and flotation circuits. 3

The reagents of this treatment comprise naphthenic acid compositions as frothers and collectors for the magnesite content, while metallic salts which will produce hydrogels in the pulp are employed to promote the action of the collector reagent and at the same time inhibit flotation of the lime-bearing and insoluble content, either with or without the inclusion of alkali salts; of

pyrophosphoric acid which exert a strong inhibiting influence on such insoluble and lime-bearing content.

Following the conditioning treatment, the pulp and reagent are subjected to the action of aeration in suitable froth flotation apparatus, and the magnesite content responding to the action of the reagent is elevated to the surface and collects in a froth for removal from the treatment by overflow or otherwise.

If desired, the tailings of this initial separation may be passed into a secondary flotation circuit comprising a cell or series of cells and subjected to aeration in the presenc of additional reagent. The froth product of this operation is collected separately from the initial froth product and will be of different grade but within the prescribed limits. However, for most operations, a singlestage flotation circuit will be sufllcient.

To illustrate the efficiency of the naphthenic acid compositions as reagents, certain test operations will be' cited and these ma be adopted as standards where the process of the present invention is to be practiced.

In the first of these, the ore treated was Margie (Luning, Nevada) magnesite having 2.21% insoluble and'4.41% CaO as impurities. This ore was ground to 100 mesh and the pulp was conditioned with 8 pounds ferric chloride and 1.5 pounds tetra-sodium pyrophosphate per ton of ore treated, with 1.6 pounds of #270 naphthenic acids per ton of ore treated as the collector reagent.

Following this conditioning treatment, the pulp was introduced into a flotation cell and a 47% recovery obtained. This product assayed 0.91% insoluble and 1.23% CaO.

A corresponding pulp was similarly treated with the FeCla reducedto 4 pounds and the pyrophosphate reduced to one pound and the naphthenic acids to 1.3 pounds-per ton of ore treated.

standard for thegrlnding circuit, which prefer- In this test, the recovery was 35% by weight and methods of my aforesaid applications a typical comparative test record is cited:

Test A l5 lauric acid Test B naphthenic acid Grade ieed Grade conc Wt. recovery, per

cen

2.75 insol./2.72 C80. 2.24 O inS0l./2.76 09.0.

2516 o insoL/Ll-i 0110.

3.768 0 insol./1.17 C80.

Al or Fe salt Caustic... Pyrophos While the foregoing examples demonstrate the suitability of the naphthenic acids as collector reagents in the treatment of ores of this character, certain other significant factors have been noted in these observations.

Thus, the degree of recovery appears to be directly related to the degree of dispersion of the naphthenic acids in the pulp. This suggests the use of a suitable emulsifying agent as a means of increasing recovery and decreasing reagent consumption.

The following comparative tests using 1.0 pound per ton of #170 naphthenic acid as reagent illustrate the improvement in recovery resulting from increased dispersion, which may be accomplished by the introduction of emulsifying agents. In each instance, 500 grams of ore were taken for test. The results follow:

Test N o.

Method of dispersion While the foregoing tests demonstrate that adequate results for commercial operation can be obtained by a simple reagent combination of naphthenic acids and iron salt, best results may be expected when the strong depressor of the class of alkali salts of pyrophosphoric acid is included in proper proportion with the hydrogelforming salts.

The relative proportions of these reagents to give optimum results will vary with different ores treated. As the desideratum is to obtain a proper balance between the strong depressor (pyrophosphate) and the weak depressor (iron salts) which will depress all the dolomite content and very little of the magnesite, tests should be made to determine the proper proportions for treating any given ore.

The variations in reagent content in the various test operations cited herein will provide a standard for such testing. Similarly, where an emulsifying agent is employed, preliminary testing should be undertaken to determine the proper proportion of such agent to the reagent.

Certain operating advantages also result from using these reagents. The froth tends to be of uniform character, less voluminous than the froths produced by other reagents, but sufficiently fragile to be broken down readily when required, thereby simplifying the treatment of the concentrate following the flotation separation.

Perhaps the greatest single advantage of the present treatment resides in the economy of the operation. The simplified reagent combination reduces both material and operating costs while its strong collecting power improves grade and recovery even with reduced reagent consumption.

As a result, the present process is particularly suited for the treatment of low grade ores, even ores of a grade lower than could be economically treated by former methods.

In the description and claims, the broad term naphthenic acid compositions will be used to designate the entire class of reagents suitable for the purposes of the present invention. This term is intended to include both naturallyoccurring products of petroleum and similar compositions manufactured therefrom. It embraces the entire class of impure crude products containing naphthenic acids or salts thereof, which in chemical classification are designated as any one or combination of nonbenzenoid cyclic carboxylic acids derived from petroleum.

The more specific term naphthenic acids as used in the specification includes the class of compositions having the formula CnHZn-QCOOH and consisting chiefly of cyclopentane carboxylic acids. For commercial purposes, these acids are designated by acid number and in the description whenever symbols such as #170, #270, etc., are employed, they refer to such acid numbers.

While the operativeness of specific members of the class has been demonstrated in the examples specifically cited herein, it will be understood that the several members of the broad class designation set forth hereinbefore are capable of giving workable results and as a consequence a wide variety in sources of reagent supply is afforded.

The metallic salts employed in the treatment function to produce a reaction product including hydrogels. For convenience in designating such compositions as a class in the description and claims, the expression hydrogel-forming salt has been selected.

The various pyrophosphate compositions employed in the process are intended to function in pulps of variable acidity or alkalinity and combine with more or less acid hydrogen or alkali. Accordingly. the term "alkali salts of pyrophosphorio acid has been selected to designate the entire class of compositions suited for this purpose and covers the use of such compositions as NazHzPzO'z, although in most treatments a tetraalkali pyrophosphate such as NaaPzoq will give secure by Letters magnesite ore pulp, a reagent mixture including at least one naphthenic acid and a hydrogelforming salt selected from the group consisting of ferric and aluminum salts, and subjecting the resulting product to aeration.

2. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture including at least one naphthenic acid, an alkali salt of .pyrophosphoric acid and a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts, and subjecting the resulting product to aeration.

3. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture including at least one naphthenic acid and ferric chloride, and subjecting the resulting product to aeration.

4. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture including at least one naphthenic acid and aluminum sulfate, and subjecting the resulting product to aeration.

5. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture including at least one naphthenic acid, tetrasodium pyrophosphate, and a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts, and subjecting the resulting product to aeration.

6. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture inclr 1- ing at least one naphthenic acid, tetrapotassium pyrophosphate, and a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts, and subjecting the resulting product to aeration.

7. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture including at least one naphthenic acid, tetraammonium pyrophosphate, and a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts, and subjecting the resulting product to aeration.

8. In a froth flotation treatment of magnesite ores, in which lime-bearing and insoluble consltuents are depressed by a mixture of a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts and a lesser quantity of an alkali salt of pyrophosphoric acid, the improvement which comprises froth floating such magnesite constituents in the presence of at least one naphthenic acid.

9. In a froth flotation treatment of magnesite ores, in which lime-bearing and insoluble constituents are depressed by a mixture of a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts and a lesser quantity of an alkali salt of pyrophosphoric acid,

the improvement which comprises froth floating such magnesite constituents in the presence of at least one naphthenic acid mixed with a reagent serving to disperse the naphthenic acid in the pulp.

, 10. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture comprising at least one naphthenic acid and a hJdrogel-forming salt selected from the group consisting of ferric and aluminum saltsdlssolved in an alcohol, and subjecting theresulting product to aeration.

11. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pu p, a reagent tu comprising at least one naphthenic acid, an alkali salt of acid, and a hydrogel-forming salt selected from the group ,consisting of ferric and aluminum salts mixed with a reagent serving to disperse the naphthenic acid in the pulp, resulting product to aeration.

12. The method of concentrating magnesite ores by flotation, vwhichcomprises introducing into a magnesite ore pulp, a reagent mixture consisting of a non-benzenoid cyclic carboxylic acid derived from petroleum, and a hydrogelforming saltselected from the group consisting of ferric and aluminum salts, and subjecting the resulting product to aeration.

13. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture consisting of a salt of a non-benzenoid cyclic carboxylic acid derived from petroleum, and a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts, and subjecting the resulting product to aeration.

14. The method of concentrating magnesi ores by flotation, which comprises introducing into ,a magnesite ore pulp, a reagent consisting of a non-benzeneoid cyclic carboxylic acid derived from petroleum, tetrasodium pyrophosphate and ferric chloride, and subjecting the resulting product to aeration.

15. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture consisting of a, non-benzenoid cyclic carboxylic acid derived from petroleum, tetrasodium pyrophosphate and aluminum sulfate, and subjection'the resulting product to aeration.

16. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture consisting of a salt of a naphthenic acid, tetrasodium pyrophosphate, and ferric chloride, and subjecting the resulting product to aeration.

17. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture consisting of a salt of a naphthenic acid, tetrasodium pyrophosphate, and aluminum sulfate, and subjecting the resulting product to aeration.

18. The method of concentrating magnesite ores by flotation, which comprises introducing into a magnesite ore pulp, a reagent mixture consisting of a non-benzenoid cyclic carboxylic acid derived from petroleum, an alkali salt of pyrophosphoric acid, and a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts, and subjecting the resulting product to aeration.

19. In a froth flotation treatment of magnesite ores, in which lime-bearing and insoluble 'constituents are depressed by a mixture of a hydrogel-forming salt selected from the group consisting of ferric and aluminum salts, and a lesser quantity of an alkali alt of pyrophosphoric acid.

'the improvement which comprises froth floating WEINIG. 

